The present invention relates generally to communication systems and methods of communication, and, especially, to communication systems and methods of communication for use in magnetic resonance imaging procedures.
In general, magnetic resonance imaging (MRI) systems require isolation from external sources of electromagnetic fields to optimize image quality. Conventional MRI systems, therefore, typically include some form of electromagnetic isolation shield or barrier. Most often, a room enclosed by copper sheeting or conductive mesh material isolates or shields the imaging system from undesirable sources of electromagnetic radiation, including the electromagnetic noise inherent in the atmosphere.
A number of powered injectors for use in MRI have been developed. These powered injectors are a potential source of electromagnetic radiation. To realize the full benefit of xe2x80x9cshieldedxe2x80x9d rooms in MRI, injector systems typically employ a controller that is isolated from the powered injector. For example, the controller may be placed outside of a shielded room (e.g., in the MRI control room) in which the MRI scanner and the powered injector operate. Such isolation prevents undesirable electromagnetic radiation generated by the injector system controller from interfering with the signals used to create the magnetic resonance images.
The external, isolated location of the system controller creates various problems associated with the installation and operation of these systems. One such problem is the need to provide a communication link between the external controller and the injector (which is located within the shielded area), without introducing extraneous electromagnetic radiation. In other words, there is a need to provide injector control circuitry while maintaining the integrity of the electromagnetic shield.
Previous attempts to solve these problems included drilling holes in the wall of the electromagnetic shield for inserting the necessary lines or, alternatively, laying the lines under a shielded floor of the imaging room. These alternatives have proven to be less than optimum, since spurious radiation can arise from the presence of the various supply cables within the shielded imaging suite. Additionally, MRI systems which employ these alternatives often require substantial site dedication and are, therefore, not very portable.
U.S. Pat. No. 5,494,036, the disclosure of which is incorporated herein by reference, discloses, in one embodiment, an improved communication link that is made through a window in an isolation room barrier. These windows are typically in the form of a glass laminate containing a conductive wire mesh, or alternatively, a window that is coated with a thin sheet of conductive material such as gold to maintain the shielding characteristics of the isolation area or room.
The above-noted embodiment of the communications link of U.S. Pat. No. 5,494,036 includes electromagnetic transceivers that operate in a frequency range which permeates the window while maintaining the integrity of the isolation barrier. The internal transceiver is positioned on the window and is tethered or attached to the injector control in the MRI shielded room via a communication line. The external transceiver is positioned on the opposite side of the window (i.e., in the MRI control room) and is connected to the injector system controller. Infrared or electromagnetic energy in the visual range are noted to provide the best results. A fiber optic communication link is also disclosed.
Although improvements have been made in communication systems for use in magnetic resonance imaging, it remains desirable to develop improved communication systems.
In one aspect, the present invention provides a system for bi-directional communication during a magnetic resonance imaging procedure using an MRI scanner and an electromagnetic isolation barrier defining an isolation area within which the scanner is positioned.
The system includes generally at least a first source of RF signals outside the frequency range of the scanner and at least a first receiver for RF signals outside the frequency range of the scanner. The first source of RF signals and the first receiver of RF signals are in communication with a system controller positioned outside the isolation area. The system also includes at least a second source of RF signals outside the frequency range of the scanner and at least a second receiver for RF signals outside the frequency range of the scanner. The second source of RF signals and the second receiver for RF signals are positioned within the isolation area.
The system of the present invention allows bi-directional communication with and control of instrumentations within the isolation barrier from the system controller located outside of the isolation barrier. Preferably, the frequency of the RF signal is above approximately 1 Gigahertz. For example, the RF signal can be in the 2.4 GHz frequency range.
The system can, for example, include a powered injector to inject a fluid medium into a patient. In this embodiment, the second receiver and the second source are preferably in communicative connection with a control unit of the powered injector. The second receiver and the second source can, for example, be connected to the injector control unit so that the injector control unit, the second receiver and the second source can be moved as a unit.
In another aspect, the present invention provides an injector system for injection of a fluid medium into a patient within an electromagnetic isolation area. The injector system includes a powered injector positioned within the isolation area and a system controller positioned outside the isolation area. The system controller includes an operator interface. The powered injector includes a first communication unit, and the system controller includes a second communication unit. The first communication unit and the powered injector are connected so that the first communication unit and the powered injector can be moved as a unit. The first communication unit is also adapted to communicate with the second communication unit by transmission of energy through the air. The energy is chosen to not create substantial interference with a magnetic resonance imaging scanner positioned within the isolation area.
The energy can be electromagnetic energy outside the frequency range of the scanner (for example, RF energy above approximately 1 Gigahertz). The energy can also be vibrational energy, sonic energy or ultrasonic energy. Furthermore, the energy can be visible light or infrared light.
The injector system can further include at least one intermediate communication unit positioned within the isolation area through which the first communication unit can communicate with the second communication unit. The first communication unit communicates with the intermediate communication by transmission of energy through the air. A plurality of such intermediate communication units can be positioned within the isolation area to facilitate communication.
In another aspect, the present invention provides a system for use in an MRI procedure that includes an MRI scanner positioned on a first side of an electromagnetic isolation barrier and an injector control unit to control injection of a fluid medium into a patient. The injector control unit is also positioned on the first side of the isolation barrier. The system also includes a system controller positioned on a second side of the isolation barrier. The injector control unit includes a first communication unit, and the system controller includes a second communication unit. The first communication unit is adapted to communicate with the second communication unit in a bi-directional manner by transmission of energy through the air. As described above, the energy is chosen to not create substantial interference with a magnetic resonance imaging scanner.
The present invention also provides a communication system for use in an MRI procedure that includes a first communication unit positioned within a shielded housing on an interior side of the isolation barrier. The first communication unit includes a first receiver and a first transmitter. The communication system also includes a second communication unit positioned on an exterior side of the isolation barrier. The second communication unit includes a second receiver and a second transmitter. The first communication unit is in connection via optical cabling with a first light transmitting device positioned on an interior side of the isolation barrier adjacent a viewing window in the isolation barrier. The second communication unit is in connection via optical cabling with a second light transmitting device positioned on the exterior side of the isolation barrier adjacent a viewing window in the isolation barrier. The first communication unit and the second communication unit communicate via transmission of optical energy between the first light transmitting device and the second light transmitting device.
In one aspect, the first communication unit is positioned within a shielded housing of an injector control unit. The first light transmitting device can include a first lens assembly in communication with the first transmitter via optical cable and a second lens assembly in communication with the first receiver via optical cable. Likewise, the second light transmitting device can include a third lens assembly in communication with the second receiver via optical cable and a fourth lens assembly in communication with the second transmitter via optical cable. The first lens assembly and the third lens assembly are preferably in general alignment to enable communication between the first transmitter and the second receiver via transmission of light therebetween. Similarly, the second lens assembly and the fourth lens assembly are preferably in general alignment to enable communication between the first receiver and the second transmitter via transmission of light therebetween.
In another aspect, the present invention provides a method of controlling an injector within an isolation barrier of a magnetic resonance imaging area, including the steps of: transmitting RF signals outside the frequency range of the magnetic resonance imaging scanner from a system control unit positioned outside the isolation barrier to an injector control unit positioned inside the isolation barrier, the system control unit including an operator interface; and transmitting RF signals outside the frequency range of the magnetic resonance imaging scanner from the injector control unit to the system control unit.
The present invention also provides a method of transmitting data between the exterior of an isolation barrier of a magnetic resonance imaging area and the interior of the isolation barrier, including the steps of: positioning a first passive light transmitting assembly adjacent a translucent window in the isolation barrier on the outside of the isolation barrier; positioning a second passive light transmitting assembly adjacent the window on the interior of the isolation barrier in general alignment with the first light transmitting assembly such that light energy can be transmitted therebetween, and connecting the second light transmitting assembly via optical cable to a communication unit positioned within a shielded housing within the isolation barrier.
Numerous other objects and advantages of the present invention will be apparent from the following drawings and detailed description of the invention and its preferred embodiments.